Load measuring pins can be utilized to measure load and force and provide overload protection. The pins can be mounted into machines in place of normal shafts and can be fitted with strain gauges, allowing them to produce a signal proportional to the measured load. Load measuring pins are typically an electronic device or transducer that can be utilized to convert a force into an electrical signal. Load measuring pins are designed for many diverse applications as direct replacements for clevis or pivot pins. Such components can be typically employed in the context of rope, chain and brake anchors, sheaves, shackles, bearing blocks, pivots and other similar devices.
Load measuring pins operate based on a shearing principle. That is, the deformation of the load-measuring pin proportional to a load can be measured through a strain gauge bridge integrated in the load pin. The load pin includes a relatively massive constraint, which functions as rigid members for directing the force to be measured to the strain gauge bridge while remaining substantially unaffected by extraneous forces. The constraints should be independent of typical extraneous forces that are not desired as measured quantities.
When force is applied to the load-measuring pin along its sensitive axis, the effect on the strain gauge bridge results in an output signal proportional to the applied force. The powering of the strain gauge bridge, as well as the amplification of its output signal voltage, can be performed either by an external amplifier or through an internal amplifier. The amplifier allows monitoring of several levels depending on the execution.
The majority of prior art load measuring pins can be designed with external grooves that can be machined into the outer circumference of the load pin. Such external grooves are required to provide separation between the loading surfaces and the constraint surfaces and to minimize bending stresses, which cause inherent non-linearity. These external grooves are susceptible to corrosion and hydrogen damage from plating operations, which are required to generate the bearing surface necessary in an aircraft breaking system. Similarly, the load pins do not provide an independently loaded constraint locations and a smooth internal bore for associating the strain gauges. These factors affect the performance of the load-measuring pin.
Based on the foregoing it is believed that a need exists for an improved load-measuring pin as disclosed in further detail herein.